The present invention generally relates to a display apparatus such as a liquid crystal display or the like, and more particularly, to a display apparatus which adds a switching element for each of the display picture elements arranged in a matrix shape so as to effect the active matrix driving operation.
A liquid crystal display is widely used as a display apparatus which is smaller in size and lighter in weight. An active matrix shaped liquid crystal display apparatus which has, for example, switching transistors added respectively to the respective display picture elements, especially with the display picture elements being arranged in the matrix shape, sequentially selects the display picture elements by the use of the switching effect of the switching transistor. It further applies the display voltage in an embodiment corresponding to the display data so as to effect the displaying operation. Such an active matrix type of liquid crystal display apparatus is often used as a monitor apparatus and so on for a television receiver, a video tape recorder, as a display apparatus which is higher in contrast, and is capable of gradation display of the multiple stages.
A block diagram of a liquid crystal display apparatus 1 in such a conventional embodiment is shown in FIG. 10. The liquid crystal display apparatus 1 is provided with a display part 3, with the display picture elements 2 being arranged in many matrix shapes, and the one-terminals of the switching transistors 4 being connected respectively with the respective display picture elements 2. The other terminals of the respective switching transistors 4 are connected respectively with the column electrodes 5, with the gates of the switching transistors 4 being connected respectively with the row electrodes 6-1, 6-2, . . . , 6-n (when necessary, they are generically named with reference character 6). The respective row electrodes 6 are respectively connected with the scanning circuit 7, and the column electrodes 5 are connected with the data signal circuit 8, so that these circuits 7, 8 are controlled in the operation by the control circuit 9.
The scanning circuit 7 makes the respective switching transistors 4 conductive, which are connected with the row electrodes 6, with the row electrodes 6 being sequentially provided as, for example, high level. At this time, the display voltage corresponding to the desired display is applied upon respective row electrodes 5. Thus, the respective display picture elements 2 effect the corresponding displays. Such display is repeated for each of the respective row electrodes 6 so as to complete the display of one image portion. Such processing is repeated, for example, each 1/60 seconds, or 1/30 seconds so as to effect the display.
When such a liquid crystal display 1 is used as a so-called liquid crystal television receiving apparatus, the picture signal of, for example, a NTSC system is used as the signal for display use. In such a case, the picture signal is received by an antenna 10. The desired picture signal is separated by a receiving circuit 11 including, for example, a detection circuit, an amplification circuit and so on. After it has been converted into the digital signal by the analog/digital converting circuit (hereinafter referred to as A/D converting circuit) 12, the various types of signal processing is effected by the signal processing circuit 13. It is then converted into the analog signal by the digital/analog converting circuit (hereinafter referred to as D/A converting circuit). It is subsequently fed into the data signal circuit 8. Further also the reference signal Sy is inputted into the circuits 8, 9 so as to effect the given scanning operation.
In such a matrix type of liquid crystal display apparatus 1 as described hereinabove, when the display is effected in accordance with the television picture signal, a driving system for feeding, into the liquid crystal display apparatus 1, the television signal by the line sequential system for each of the horizontal scanning periods is used when the number of the row electrodes 6 is close to the number of the effective scanning lines (approximately 480 lines in the NTSC system) of the television signals, or when it is close to 1/2 the number of effective scanning lines. At this time, when the row electrodes 6 are close in number to the effective scanning lines, the display of one image portion of the display part 3 is effected for each of the frame periods. When the line of the row electrodes is close in number to the effective scanning lines, the display of one image of the display part 3 is effected for each of the field periods.
When the number of the row electrodes 6 is comparatively small with respect to the number of the above described effective scanning lines and 1/2 the number thereof, the horizontal scanning lines within one vertical scanning period of, for example, the picture signal are allotted into the row electrodes 6 from the upper side in the vertical scanning direction when such display as described hereinabove has been effected, the two electrodes 6 are allotted, completed before the picture signals of all the scanning line number portion are inputted, and the display with the lower portion of the proper image being omitted in it in the display part 3. When the residual picture signals have been displayed by the display part 3, with the pictures signals of the omitted portion being removed from the head of one vertical scanning period, the display with the upper portion of the proper picture signal being omitted in it is effected when the residual picture signals have been displayed in the display part 3.
When the number of the row electrodes 6 is comparatively smaller than the number of the effective scanning lines 1/2 and the number thereof, a method of thinning out the picture signals corresponding to the specified scanning lines among the picture signals within one vertical scanning period is used so as to apparently display the proper whole image. This method is similarly effected even in a case where, for example, the picture signals of a PAL system (the number of the scanning lines is 625) are converted into the signals of a NTSC system (the number of the scanning lines is 525) or in the other cases. Such a signal processing, as performed at present, of thinning out the picture signal corresponding to a scanning line or the picture signal corresponding to a plurality of scanning lines is effected in the digital circuit such as a signal processing circuit 13 or the like shown in FIG. 10 in terms of the processing accuracy or the like. Therefore, such an A/D conversion circuit 12, a signal processing circuit 13, a D/A conversion circuit 14 and so on as described hereinabove become indispensable, with a problem that the circuit structure becomes extremely complicated.